<html>
	<head>
		<meta charset="utf-8" />
		<title>jquery.back2top</title>
	</head>
	<body style="height:600%;">
		<div id="top"></div>
	</body>
</html>
<script type="text/javascript" src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>
<script type="text/javascript" src="jquery.back2top.js"></script>
<script type="text/javascript">
	$(document).ready(function(){
		$('#top').back2top();
	});
</script>